1. Field of the Invention
The present invention relates to a tubular vibration-damping device used for a vibration-damping connecting rod such as a torque rod, and to a vibration-damping connecting rod using the same, and further to a manufacturing method thereof.
2. Description of the Related Art
A vibration-damping connecting rod has been known as a unit utilized as a torque rod that supports torque reaction force of a power unit, and the like. This vibration-damping connecting rod includes a rod main body and a tubular vibration-damping device provided at least at one end of the rod main body. The tubular vibration-damping device has a structure such that an inner shaft member is inserted into an outer tubular member, while the inner shaft member and the outer tubular member are elastically connected to each other by a main rubber elastic body. For example, the vehicular-side torque rod bush described in Japanese Unexamined Patent Publication No. JP-A-2006-002908 is such a one.
As shown in JP-A-2006-002908, the rod main body of the torque rod, which is fixed to the power unit side as a vibration source, is generally mounted to the outer tubular member of the tubular vibration-damping device of the torque rod.
In order to set a broader linear region of the vibration characteristics, the amount of displacement of the outer tubular member relative to the inner shaft member needs to be well allowed. Therefore, once the outer tubular member is mounted to the power unit side, a large space is required around the outer tubular member on the vehicular body side as a vibration-damping target member. In addition, the displacement of the outer tubular member relative to vehicular body tends to cause a problem of interference between the outer tubular member and other members mounted to the vehicular body.
To address this problem, European Unexamined Patent Publication No. EP 2 105 629 discloses that the outer tubular member is pressed into a holder such as a suspension member or the like and mounted to the vehicular body. According to the structure disclosed by EP 2 105 629, two tubular vibration-damping devices are overlapped with each other in the axial direction, while the rod main body is inserted into a concave portion provided in the overlapping portion of the inner shaft member via a cutout provided in the overlapping portion of the outer tubular member so as to be fixed to the inner shaft member.
However, since the main rubber elastic body is divided into two sections according to the structure of EP 2 105 629, the rubber volume of each main rubber elastic body is reduced to lower the degree of tuning freedom of vibration-damping characteristics and the durability thereof. In addition, since the inner shaft member supporting the rod main body is directly bonded to the main rubber elastic body, when the inner shaft member of each tubular vibration-damping device is brought closer to each other to hold the rod main body in between, the elasticity of the main rubber elastic body works to prevent such displacement of getting closer to each other, possibly causing difficulty in assembling the rod main body.